Shape Analysis Research Articles

Statistical shape analysis of the Chinese external ear for ergonomic design of in-ear products.

3D scanning capture complex ear morphology, but most research focuses on dimensions defined by product design or ergonomic guidelines, often missing crucial 3D details, especially those of ear canal for in-ear product design. This study conducted a statistical shape analysis on the 3D geometry of the cavum concha and the external auditory meatus (EAM) using 1195 scans of Chinese ears. A surface registration method was adopted to standardise and align ear models for shape analysis. Principal component analysis (PCA) generated statistical models of ear shapes, with the most significant variation reflecting the overall width of the cavum concha, explaining 29.63% of the variation. The k-means++ algorithm was employed to classify ear shapes using the first 15 principal component scores, identifying four shape categorisations. Significant variations and shape modes of ear shape were identified, and the derived statistical shape models provide essential 3D references for the ergonomic design of ear-related products.

Three-Dimensional Geometric Morphometric Characterization of Facial Sexual Dimorphism in Juveniles

Background: The characterization of facial sexual dimorphic patterns in healthy populations serves as valuable normative data to tailor functionally effective surgical treatments and predict their aesthetic outcomes and to identify dysmorphic facial traits related to hormonal disorders and genetic syndromes. Although the analysis of facial sexual differences in juveniles of different ages has already been investigated, few studies have approached this topic with three-dimensional (3D) geometric morphometric (GMM) analysis, whose interpretation may add important clinical insight to the current understanding. This study aims to investigate the location and extent of facial sexual variations in juveniles through a spatially dense GMM analysis. Methods: We investigated 3D stereophotogrammetric facial scans of 304 healthy Italians aged 3 to 18 years old (149 males, 155 females) and categorized into four different age groups: early childhood (3–6 years), late childhood (7–12 years), puberty (13–15 years), and adolescence (16–18 years). Geometric morphometric analyses of facial shape (allometry, general Procrustes analysis, Principal Component Analysis, Procrustes distance, and Partial Least Square Regression) were conducted to detail sexually dimorphic traits in each age group. Results: The findings confirmed that males have larger faces than females of the same age, and significant differences in facial shape between the two sexes exist in all age groups. Juveniles start to express sexual dimorphism from 3 years, even though biological sex becomes a predictor of facial soft tissue morphology from the 7th year of life, with males displaying more protrusive medial facial features and females showing more outwardly placed cheeks and eyes. Conclusions: We provided a detailed characterization of facial change trajectories in the two sexes along four age classes, and the provided data can be valuable for several clinical disciplines dealing with the craniofacial region. Our results may serve as comparative data in the early diagnosis of craniofacial abnormalities and alterations, as a reference in the planning of personalized surgical and orthodontic treatments and their outcomes evaluation, as well as in several forensic applications such as the prediction of the face of missing juveniles.

Numerical analysis of absorber tube shapes in PCM-integrated parabolic trough solar collectors

Numerical analysis of absorber tube shapes in PCM-integrated parabolic trough solar collectors

Geometric morphometrics approach for classifying children’s nutritional status on out of sample data

Current alignment-based methods for classification in geometric morphometrics do not generally address the classification of new individuals that were not part of the study sample. However, in the context of infant and child nutritional assessment from body shape images this is a relevant problem. In this setting, classification rules obtained on the shape space from a reference sample cannot be used on out-of-sample individuals in a straightforward way. Indeed, a series of sample dependent processing steps, such as alignment (Procrustes analysis, for instance) or allometric regression, need to be conducted before the classification rule can be applied. This work proposes ways of obtaining shape coordinates for a new individual and analyzes the effect of using different template configurations on the sample of study as target for registration of the out-of-sample raw coordinates. Understanding sample characteristics and collinearity among shape variables is crucial for optimal classification results when evaluating children’s nutritional status using arm shape analysis from photos. The SAM Photo Diagnosis App© Program’s goal is to develop an offline smartphone tool, enabling updates of the training sample across different nutritional screening campaigns.

The structural effects of transcranial magnetic stimulation on hippocampal subfields in Alzheimer's disease

Aim: This study investigates the structural effects of repetitive transcranial magnetic stimulation (rTMS) on hippocampal subfields and cortical shape metrics in Alzheimer’s disease (AD) patients. Using high-resolution MRI segmentation and analysis via Hippunfold, we aim to elucidate TMS-induced structural changes and assess its potential neuroprotective role. Methods: This retrospective study included 17 AD patients and 18 healthy controls (HC). AD patients underwent 20 Hz rTMS targeting the left lateral parietal cortex over 10 sessions across two weeks. Magnetic resonance imaging (MRI) data were acquired before and after rTMS and analyzed with Hippunfold to segment hippocampal subfields and extract cortical thickness and shape metrics. Statistical analyses were performed to compare subfield volumes and cortical metrics between groups and across time points. Results: Hippocampal volumetric analysis revealed significant atrophy in subfields such as Cornu Ammonis 1, (CA1), CA2, CA4, dentate gyrus (DG), subiculum, and stratum radiatum-lacunosum-moleculare (SRLM) in AD patients compared to HC. Although no significant volumetric recovery was observed post-TMS, a further decline was noted in the right CA3 subfield (p=0.005), highlighting progressive atrophy. Cortical shape analyses showed significant reductions in hippocampal thickness (p

Athletic shapeshifting of the right ventricle: 3D echocardiography-derived global and regional shape analysis in elite athletes

Abstract Intense physical activity poses marked hemodynamic strain on the right ventricle (RV), as during exercise, RV is subjected to a proportionally higher pressure and volume overload than its left counterpart. While the morphological changes of the left ventricle can be characterized using pre-defined reference shapes (cone and sphere), the complex structure of the RV cannot be captured similarly. Therefore, the exercise-induced changes in the RV's global and regional shape have not been directly investigated. Our aim was to develop a 3D echocardiography (3DE)-based method to quantify the global and regional shape metrics of the RV in a large cohort of elite athletes. Elite athletes (n=138) and healthy, sedentary volunteers (n=104) were enrolled and underwent 3DE to measure RV volumes and ejection fraction (EF). 3D RV endocardial mesh models were reconstructed at end-diastole and end-systole to quantify regional curvature indices along 5 clinically relevant parts of the RV (apex, septum, free-wall, outflow tract, and inflow tract). Zero curvature depicts a flat surface, whereas a more positive or negative curvature represents a more convex or concave surface, respectively. Regarding the RV’s global shape, hemi-conicity and hemi-sphericity indices were introduced (Figure 1). First, the longitudinal height of the 3D RV mesh was defined. To calculate hemi-sphericity index, a hemisphere (with a radius that is half the height of the RV mesh) was created. Then, the volume of this hemisphere and the volume of the RV mesh were compared (a higher volume ratio depicts a more spherical shape). To calculate hemi-conicity index, a half-cone (whose height equals the RV’s height and volume equals the RV mesh’s volume) was defined. Then, the angle at the top of the half-cone was evaluated (a more acute angle describes a more conical shape). As expected, athletes had higher RV end-diastolic (EDV; 165±36 vs. 146±44 ml, p<0.001) and end-systolic volumes (ESV; 75±22 vs. 65±23, p<0.005), whereas RV EF did not differ in the two groups. Regional curvature analysis showed that in athletes, the septum of the RV was significantly flatter (-0.4±9 vs. 6.7±7.7, p<0.001), along with the RV free-wall curvature index that also depicted a significantly flatter shape (57.9±8.3 vs. 61.2±7.7, p<0.001) compared to controls. The global shape assessment revealed that the RV of the athlete’s heart had a more conical shape, as the hemi-sphericity volume ratio was significantly lower (0.79±0.17 vs. 1.19±0.40, p<0.001), and the hemi-conicity angle exhibited a more acute angle (63.8± 5.7 vs. 74.1±9.1, p<0.001) both pointing towards a conical remodeling. The assessment of 3D echocardiography-derived regional and global shape metrics revealed a different, more conical geometry in the athletes’ RV. Our novel method may enable a more precise quantification of the RV's unique, exercise-induced geometrical remodeling. Figure 1

Exploring bandgap tuning and vibration isolation performance of innovative negative stiffness metastructures

Negative stiffness metamaterials with tunable bandgap properties present promising applications in vibration control and mechanical property enhancement. This study proposes and compares two metastructures with unit cells exhibiting negative stiffness, achieved through the snap-through behavior of a top beam under displacement. The vibration isolation performance of these models is investigated through theoretical and finite element analyses, with experimental verification of transmission results. Both structures demonstrate significant band gaps, and mode shape analysis of the unit cells reveals the mechanisms underlying bandgap formation. A parametric study examines the effects on bandgap characteristics, including opening and closure, as well as transmission behavior in arrayed configurations. Results indicate that both metamaterial models, with their negative stiffness properties, can create multiple band gaps and achieve excellent vibration isolation, making them strong candidates for vibration isolation applications in engineering structures.

Cotton From Industrial Waste Modified for Effective Absorption of Oil Spills

ABSTRACTA primary emphasis of this investigation is the utilization of discarded cotton fiber. Oil sorbent from cotton was developed by changing the hydrophilic surface of waste cotton fiber to a hydrophobic surface by acetylation treatment. Change in the surface structure of the fiber was confirmed by confirmed through various analytical techniques, including Fourier‐transform infrared (FTIR) spectroscopy, drop shape analyzer (DSA100), and scanning electron microscope (SEM). Compared to commercial oil sorbents (polypropylene), diesel and engine oil were shown to have much greater oil sorption capacities (20.07 and 23.89 g/g, respectively). Acetylated cotton fibers are easily disposed of after the fifth cycle and have remarkable oil sorption capacities (23.89 g/g). After the fifth cycle, regenerated sorbent is eco‐friendly and can supply biopower plants. They also support environmental sustainability goals.

Application of shape analysis for the identification of pelagic fish stocks

Abstract This study explores local variations in body and otolith shape of Trachurus trachurus from the Ibero-Mauritanian coastal stock in the South European Atlantic Shelf ecoregion, essential for effective stock management. We used geometric morphometrics and wavelet functions to analyze samples from Galicia, Peniche, and the Gulf of Cádiz. Comparing fresh and frozen specimens revealed significant shape changes due to freezing. Our results confirm that unique environmental conditions in the South European Atlantic Shelf ecoregion contribute to distinct local populations. The northern population had a more elongated body and lanceolate otoliths, while the southern population displayed a wider body and oval otoliths. Central region specimens exhibited intermediate characteristics. Four distinct morphotypes were identified, with region-specific distributions. These findings suggest local adaptations within the Ibero-Mauritanian stock, emphasizing the need to account for these differences in management strategies to ensure sustainability. Future studies should include larger, more diverse samples, especially from the Mediterranean, to further understand stock structure.

Motif clustering and digital biomarker extraction for free-living physical activity analysis

BackgroundAnalyzing free-living physical activity (PA) data presents challenges due to variability in daily routines and the lack of activity labels. Traditional approaches often rely on summary statistics, which may not capture the nuances of individual activity patterns. To address these limitations and advance our understanding of the relationship between PA patterns and health outcomes, we propose a novel motif clustering algorithm that identifies and characterizes specific PA patterns.MethodsThis paper proposes an elastic distance-based motif clustering algorithm for identifying specific PA patterns (motifs) in free-living PA data. The algorithm segments long-term PA curves into short-term segments and utilizes elastic shape analysis to measure the similarity between activity segments. This enables the discovery of recurring motifs through pattern clustering. Then, functional principal component analysis (FPCA) is then used to extract digital biomarkers from each motif. These digital biomarkers can subsequently be used to explore the relationship between PA and health outcomes of interest.ResultsWe demonstrate the efficacy of our method through three real-world applications. Results show that digital biomarkers derived from these motifs effectively capture the association between PA patterns and disease outcomes, improving the accuracy of patient classification.ConclusionsThis study introduced a novel approach to analyzing free-living PA data by identifying and characterizing specific activity patterns (motifs). The derived digital biomarkers provide a more nuanced understanding of PA and its impact on health, with potential applications in personalized health assessment and disease detection, offering a promising future for healthcare.

Assessing the Greater Sciatic Notch With 2‐D Shape Analysis for Sex Estimation

Assessing the Greater Sciatic Notch With 2‐D Shape Analysis for Sex Estimation

Is the skull of the black-headed gull dimorphic? Analysis of shape variation

The black-headed gull (Chroicocephalus ridibundus) is a small bird belonging to the Laridae family. Their distribution and breeding broad area primarily cover the northern part of the Eurasian continent. Gulls are considered monomorphic birds, and distinguishing the sexes based on external morphological features is extremely difficult. In this study, a 3D shape analysis of the skull of black-headed gulls from central-northern Poland was performed to reveal the variation in shape between individuals and whether male skulls differ from females. For these purposes, 82 skulls were used (32 females and 50 males). 3D surface models of the skull were extracted using computed tomography. Twenty-one landmarks were designed on each skull. The principal components method was used to assess the variability of skull shapes. The first two principal components accounted for 48.28% of the cumulative shape variation. The most significant shape variation relative to PC1 was observed in the braincase. Positive PC2 values reflected the neurocranium expanding more rapidly dorso-ventrally with a wider orbit, and the nasofrontal hinge moved dorsally. According to the Procrustes ANOVA, the centroid size was statistically different between the sexes (p < 0.0001). Male skulls were longer than females. Neurocranium was wider in male gulls. The nasofrontal hinge was more caudal in females. The results of this study are consistent with the observations of other authors applying linear morphometry.

Generating High-Fidelity Clothed Human Dynamics with Temporal Diffusion

Clothed human modeling plays a crucial role in multimedia research, with applications spanning virtual reality, gaming, and fashion design. The goal is to learn clothed human dynamics from observations and then generate humans with high-fidelity clothing details for motion animation. Despite tremendous advancements in clothing shape analysis by existing approaches, the community still faces challenges in generating convincing visual effects of cloth dynamics, maintaining temporally smooth clothing details, and handling diverse clothing patterns. To address these challenges, we introduce ClothDiffuse, a temporal diffusion model that seamlessly integrates three key components into this task: temporal dynamics modeling, iterative refinement, and diversified generation. Our approach begins by using an encoder to extract high-level temporal features from input human body motions. These features are combined with a learnable pixel-aligned garment feature, serving as prior conditions for the shape decoder. The decoder then iteratively denoise Gaussian noise to produce clothing deformations over time on the input unclothed human bodies. To ensure that the results align with observations and adhere to physical plausibility for clothing shape inference, we propose two physics-inspired loss functions that preserve the intra-frame distances and inter-frame forces of clothing points. Additionally, the stochastic nature of the denoising process allows for the generation of diverse and plausible clothing shapes. Experiments show that our approach outperforms state-of-the-art methods in chamfer distance and visual effects, particularly for loose clothing such as dresses and skirts. Furthermore, our approach effectively adapts to out-of-domain clothing types and generate realistic clothes dynamics.

Hiatus and pelvic floor failure patterns in pelvic organ prolapse: A 3D MRI study of structural interactions using a Level III conceptual model.

A large urogenital hiatus in Level III results in a higher risk of developing pelvic organ prolapse after birth and failure after prolapse surgery. Deepening of the pelvic floor and downward rotation of the levator plate have also been linked to prolapse. Currently we lack data that evaluates how these measures relate to one another and to prolapse occurrence and size. This study uses measurements from a published conceptual model to compare women with and without prolapse to determine the magnitude of difference between cases and controls and to quantify the interrelationships among different aspects of pelvic floor shape and structure. Ninety-one women with anterior predominant prolapse and uterus in situ who had 3D MRI and 30 similar women with normal support were studied. Resting scans were used to avoid the influence of the prolapse dilating the hiatus. Measurements assessed three domains: hiatus size (urogenital and levator hiatus); length of the surrounding pelvic floor muscles (pubovisceral, puborectal, iliococcygeal muscles); the shelf-like posterior pelvic floor (levator plate shape, levator bowl volume), and bony pelvic dimensions. Effect sizes were calculated and principal component shape analysis performed to evaluate levator plate shape. A-scores were calculated and a value greater than 1.68 (95th percentile) was considered the "failure" criterion. Frequency and severity of structural support site failure were analyzed by prolapse size. Resting urogenital and levator hiatal areas were 68% and 59% larger in the prolapse group compared to controls. These area enlargements were 2-4 times larger than the anterior-posterior dimension enlargements (urogenital hiatus 36%; levator hiatus 13%). The greatest muscle length differences between groups occurred in the pubovisceral (34%) and puborectal (25%) muscles compared to the iliococcygeal muscle (8%)-roughly half the area differences. Levator bowl volume was 63% deeper with prolapse. Urogenital hiatus and levator hiatus areas were strongly correlated with pubovisceral and puborectal muscle length (.7 to .8), while iliococcygeal muscle length had lower correlations (.4 to .5). Levator bowl volume correlated strongly with hiatal enlargement (.7 to .8) and muscle length (pubovisceral and puborectal muscles), moderately so with levator plate and iliococcygeal muscle, and weakly with bony dimension. Failure frequency increased with prolapse size for urogenital hiatus anterior-posterior (p=.001) and area (p=.019). By contrast, levator hiatus area was similar for all prolapse sizes (p=.288), while levator hiatus anterior-posterior failure was more common in larger prolapses (p=.018) but with smaller percentages of failure than levator hiatus area (p<.01). Both levator bowl volume (p=.015) and levator plate (p=.045) trended toward increasing failure with larger prolapse sizes. Among women with enlarged urogenital hiatus at straining, 43% and 28% had normal urogenital hiatus anterior-posterior and area at rest, respectively. Changes in the shape and dimensions of the pelvic floor are complex and are not captured by a single measure (such as the urogenital hiatus anterior-posterior dimension, which does not capture its lateral expansion). The failure patterns were different between small and large prolapses. Understanding why could lead to improved prevention and treatments for Level III failures.

Development and evaluation of a polymer material-based formulation for non-surgical nasolabial fold reduction.

Currently, nasolabial folds are mainly removed by invasive procedures, resulting in long-lasting changes, as non-surgical user-implementable alternatives are scarce and inefficient. For example, the use of coating films for this purpose has thus far faced substantial difficulties because such films should combine the antithetical properties of shrinkability and flexibility. Herein, we challenge this status quo by identifying a polymer that simultaneously exhibits shrinkability and flexibility and using this polymer to develop a cosmetic formulation for immediate and non-invasive nasolabial fold removal. The developed formulation, namely a solution of norbornene/tris(trimethylsiloxy)silylnorbornene copolymer in disiloxane, was tested on a group of Japanese women using visual evaluation, three-dimensional shape analysis and ultrasonography. The polymer film obtained upon drying the formulation was subjected to shrinkage and flexibility tests, and its synchronization with the skin was examined using optical microscopy. The free volume of the polymer films was evaluated using positron annihilation measurements and molecular dynamics simulations. Upon application, the liquid formulation rapidly dries to produce a skin-synchronized polymer film that exhibits significant drying-induced shrinkage without cracking, thereby exerting a lift-up effect and inducing changes in the internal skin structure to efficiently reduce the nasolabial fold, providing a feeling of rejuvenation. On average, the proposed treatment decreases the nasolabial fold depth by 1 mm, increases the opening angle of the nasolabial fold by 11.5° and reduces the hypodermis thickness by 0.2 mm. Our results facilitate the development of cosmetic products targeting the nasolabial fold and inspire further research in this field.

Prenatal Diagnosis of Nonsyndromic Craniosynostosis: A Scoping Review.

Craniosynostosis is rarely diagnosed in utero. Prenatal diagnosis has the potential to improve patient outcomes and streamline care, however, and is becoming more feasible as technology improves. The objective of this study is to examine existing literature on prenatal diagnosis of nonsyndromic craniosynostosis. In accordance with PRISMA guidelines, Embase, Cochrane, and PubMed were searched for articles discussing prenatal diagnosis of nonsyndromic craniosynostosis via imaging studies. Studies that exclusively examined syndromic craniosynostosis were excluded. Diagnostic criteria for prenatal diagnosis of craniosynostosis. The search identified 2129 articles. And 12 articles met inclusion criteria and were included in the final analysis. Ten of 12 included studies (83.3%) utilized biometric data (biparietal and occipitofrontal diameter, cranial index) to analyze fetal head shape. Two of 12 studies (16.7%) utilized specific ultrasonic markers to identify craniosynostosis including a “brain shadowing sign.” One study (8.3%) created a systematic quantitative screening methodology with formal shape analysis for identification of sagittal synostosis. In all included studies, identification of craniosynostosis was possible in the second or third trimesters. Prenatal diagnosis of craniosynostosis is feasible and has the potential to improve patient outcomes. Creation of screening protocols and standardized metrics for sonographic diagnosis are important next steps in craniosynostosis care.

Effect of mechanical instrumentation on titanium implant surface properties.

To assess the impact of mechanical decontamination using rotary brushes on the surface topography, elemental composition, roughness, and wettability of titanium implant surfaces. Four commercially available rotary brushes were used: Labrida BioClean Brush® (LB), i-Brush1 (IB), NiTiBrush Nano (NiTiB), and Peri-implantitis Brush (PIB). Seventy-five titanium discs with sandblasted, large-grit, acid-etched (SLA) surfaces were randomly assigned to five groups (n = 15): LB, IB, NiTiB, PIB, and a control group. Each disc was treated for 60 seconds with the respective rotary brush according to the manufacturer's instructions. Surface morphology was analysed using Scanning Electron Microscopy (SEM), surface elemental composition with Energy Dispersive X-ray (EDX), surface roughness via optical profilometry, and wettability with a droplet shape analyser. SEI analysis revealed morphological changes, including scratches, flattening, and loose titanium particles in the IB, PIB, and NiTiB groups, whereas the LB group preserved the original surface morphology. SEM-EDX analysis showed that LB, PIB, and NiTiB groups closely match the control elemental composition. However, IB groups showed significantly different composition. Surface roughness values in the IB, PIB, and NiTiB groups differed significantly from the control (p < 0.05), whereas the LB group had comparable roughness values (p > 0.05). Contact angle measurements indicated enhanced wettability in IB, PIB, and NiTiB groups (p < 0.05), while the LB group exhibited values comparable to the control (p > 0.05). Mechanical decontamination of implant surfaces utilising rotary brushes can alter implant surface properties.

Multi Sign Language Recognition

The deaf and hard-of-hearing community often experiences communication barriers due to people who are not well-versed in the use of sign language.[1] This project would address this problem by developing an all-embracing machine learning (ML) model which would be able to interpret and translate the hand movements of American Sign Language (ASL) and Indian Sign Language (ISL) into corresponding spoken or written language in real time.[2] In using data from cameras, the system is designed to precisely predict and translate gestures both ASL and ISL. The solution integrates Natural Language Processing for context-aware translations and hence lets the system interpret the surrounding context for more meaningful and accurate implications. Moreover, the final project will explore the utilization of advanced Gesture recognition technologies, which might include the deep learning models and recurrent neural networks, shall enhance the system's accuracy as well as adaptability.[3] Data input multimodality will enhance gesture recognition: examples include skeletal tracking and hand shape analysis. User-friendly interface; it will be made possible for the users to interact with customization options of settings, preferences, including but not limited to language voice options.[6] Moreover, the project includes the potential for integration with other assistive technologies, such as speech-to-text devices and AR equipment among others, to provide a comprehensive communication assistant. At the end of it all, this project would empower the deaf and hard-of-hearing community by ensuring effective communication between the hearing population and the deaf and hard-of-hearing, social inclusion and access. The solution will be plentiful in schools, the workplaces, and public services, so all will be provided with the potentially useful tool of increasing accessibility and understanding.

Differentiation of Mullus barbatus and Mullus surmuletus (Perciformes, Mullidae) from Turkish waters of the Mediterranean Sea using otolith shape analyses

Differentiation of Mullus barbatus and Mullus surmuletus (Perciformes, Mullidae) from Turkish waters of the Mediterranean Sea using otolith shape analyses

The further optimization and sensitivity analysis of the shape of the double-arc aeration facilities in gentle slope open channel

Air entraining into water flow is one of the main technical measures to prevent cavitation damage in high-head discharge structures, and the most important issue is the optimization of the aerators shapes. Different body shapes result in different cavity characteristics, but there are currently few quantitative research results on the design of aerator shapes. Based on the design method of body parameters, this article uses orthogonal experimental design theory to conduct the further optimization and sensitivity analysis of the body shape of the double-arc aeration facility in a gentle slope open channel. Through range analysis and variance analysis, the influence effects and weights of the four body parameters, which are the deflector height, the offset height, water tongue drop point coefficient, and the ramp angle, acting on cavity characteristics such as cavity shape and ventilation capacity are obtained, and the most reasonable combination parameters for aeration facility are provided. This provides technical guidance for the precise design of aeration facility in practical engineering and promotes the quantification of aeration facility shape design.